1. Field of the Invention
The present invention relates to an active matrix-type display device using an electro-optic material such as liquid crystal, and more particularly, to an active matrix-type display device without intersections between scan bus lines and data bus lines on the same substrate.
2. Description of the Related Art
An active matrix-type liquid crystal display device as well as a simple matrix-type liquid crystal display device is thin, and therefore, is often used in various display devices. In this active matrix-type liquid crystal display device, since individual pixel elements are independently driven, the contrast is not reduced based upon the reduction of the duty ratio, and the angle of visibility is not reduced, even when the display capacity is increased to increase the number of lines. Therefore, the active matrix-type liquid crystal display device can enable a color display in the same way as in a cathode ray tube (CRT), and is prevalent in flat display devices.
In the active matrix-type liquid crystal display device, however, since one thin film transistor as a switching element is provided for each pixel, a complex manufacturing process is required, and equipment therefor is expensive. Also, the manufacturing yield is low. Thus, the active matrix-type liquid crystal display device is very expensive. Therefore, a panel formed by an active matrix-type liquid crystal display device has to be of a small size.
Also, in order to improve the low manufacturing yield due to the complex configuration of the active matrix-type liquid crystal display device, there has been suggested a counter-matrix active matrix-type liquid crystal device in which scan bus lines and data bus lines are formed on different substrates, so that intersections of scan bus lines and data bus lines on the same substrate are not used (see: U.S. Pat. Nos. 4,694,287, 4,717,244, 4,678,282).
In any type of active matrix-type liquid crystal device, the liquid crystal voltage fluctuates due to the generation of a DC component therein, which reduces the quality of display. For example, flickers and residual images may be generated. Particularly, for a stationary image, a burning phenomenon may occur. Also, the life-time of active matrix-type liquid crystal devices may be shortened.